This invention relates to treatment of infection caused by human herpesvirus 6 (HHV-6), and to the use of compounds in the preparation of a medicament for use in the treatment of such conditions.
When used herein, xe2x80x98treatmentxe2x80x99 includes prophylaxis as appropriate.
EP-A-141927 (Beecham Group p.l.c.) discloses penciclovir, the compound of formula (A): 
and salts, phosphate esters and acyl derivatives thereof, as antiviral agents. The sodium salt hydrate of penciclovir is disclosed in EP-A-216459 (Beecham Group p.l.c.). Penciclovir and its antiviral activity is also disclosed in Abstract P.V11-5 p. 193 of xe2x80x98Abstracts of 14th Int. Congress of Microbiologyxe2x80x99, Manchester, England Sep. 7-13, 1986 (Boyd et. al.).